... :Within 3days 4.Manufacturer copper heat pipe DescriptionVacuum tube58-1800mm co-axial structure high borosilicate 3.3 glass vacuum tube with tube wall ... years1,vacuum tube length:47/1500mm,58/1800.2,vacuum tubes:15pcs,18pcs,20pcs,24pcs,30pcs3,Outer tank material:202stainless steel ... water is full,it will close the valve automatically copper heat pipe for solar collector